Drying apparatus



Feb. 23, 194-3. GAUTREAU 2,311,824

DRYING APPARATUS I Filed April 50, 1941 Figl 26 27. s2 as ierfio'r. hur G. Qu'i'remu Patented Feb. 23, 1943 UNITED STATES PATENT OFFICE 1 Claim.

This invention relates to drying apparatus of the type comprising an elongated drying space or passage through which the material to be dried is advanced from one end to the other and in which said material becomes dried during its advancing movement.

My improved drying apparatus is especially adapted for drying fibrous material in a loose condition, such, for instance, as wool, cotton, etc., although the invention is well adapted for drying material in granular or powdered form.

My improved drying apparatus comprises a drying chamber, preferably in the form of a rotary horizontal cylinder, and'one of the objects of the invention is to provide a construction wherein the cylinder is provided with a continuous drying passage through which the material to be dried is advanced and which is several times longer than the length of the cylinder. By this means it is possible to secure the advantages of a relatively long drying chamber in an apparatus that takes up a relatively small amount of floor space.

This end is accomplished by providing the horizontal rotary cylinder with a helical passage extending from one end to the other thereof, and providing means for depositing the material to be dried into the passage at one end of the cylinder, the construction being such that as the cylinder is rotated, the tumbling action which the material in said passage receives due to the rotary movement of the cylinder will cause the material to be advanced through the helical passage.

The helical shape of the passage not only provides a passage having an efiective length greatly in excess of the length of the cylinder,

- but it also serves to give the material a for ward feeding movement as the cylinder is rotated.

The drying of the material in said passage may be accomplished either by circulating a drying medium through the passage or by applying heat externally to the cylinder.

In order to give an understanding of the invention, I have illustrated in the drawin some selected embodiments thereof which will now be described, after which the novel features will be pointed out in the appended claim.

In the drawing:

Fig. l is a longitudinal sectional view through a drying apparatus embodying my invention.

Fig. 2 is a section on the line 22, Fig. 1.

Fig. 3 illustrates a slightly diiferent form of the invention.

As stated above, the drying chamber of my improved apparatus is in the form of a hollow cylinder 3 which is mounted in any suitable way so that it can be rotated about its axis. As herein shown, the cylinder is mounted on suitable supports 4. The cylinder is so constructed as to provide a helical passage extending from one end to the other thereof. One way of accomplishing this is to provide a cylinder with a core member 5 extending axially thereof, and then to employ a helical web or vane 6 which encircles the core and which extends from the core to the wall I of the cylinder 3. The cylinder 3, the vane 5 and the core 5 are all made rigid with each other as a unitary structure. The space between the successive turns of the helical Web 6 is in the form of a helical passage 8 which extends from one end to .the other of the cylinder, the opposite sides of which are formed by the helicoidal surfaces 9 and ID of the vane or web 5.

The ends of the cylinder are closed by stationary heads and 24. The head 24 has an opeigng 23 which communicates with a hopper H having an open top into which the material to be dried may be deposited. The stationary head I2 is provided with a discharge opening l3 which leads to a discharge pipe It.

The cylinder 3 is provided on its interior with a plurality of lifting vanes l5 which extend longitudinally, and some suitable means is provided for rotating the cylinder on its support 4. While any means for this purpose may be employed, I have herein shown the cylinder as provided with a ring gear it which is connected through suitable reducing gears with a motor ll. The motor is provided with a pinion [8 on its shaft which meshes with a larger gear l9 on a countershaft 20, and said shaft 20 has a pinion 2i thereon which meshes with the ring gear l6. Any other appropriate speed-reducing means might be employed, however, without departing from the invention.

The material 22 which is delivered to the hopper II will pass through the opening 23 of the head 24 into the helical passage 8 and the rotative motion or the cylinder 3 will give the material a tumbling action in said passage.

The cylinder is rotated in the direction of the arrows a in Fig. l, and any portion of the material 22*which is picked up by any lifting vane I5 will be dropped from said vane before the latter reaches the top of the cylinder, as shown at b in Fig. 2. The material which is thus dropped from any lifting vane will strike the inclined hellcoidal surface l and slide down such surface toward the bottom of the cylinder, and will thus be advanced a slight distance toward the discharge end of the cylinder due to the inclination of said surface. As such portion of the material is again picked up by and dropped from a lifting vane l5 of the rotating cylinder, it will again fall onto the inclined helicoidal face l0 and will again slide down the face and thus be advanced another increment toward the discharge end of the cylinder. Hence, any material which is delivered to the left hand end of the cylinder in Fig. 1 will not only have a tumbling action due to the operation of the lifting vanes l5, but because of the helicoidal shape of the surface In of the vane 6, the material will have a progressive movement from the left hand end of the cylinder to the right hand end.

Means are provided for drying the material 22 while it is being tumbled in and advanced through the helical passage 8. In the construction shown in Figs. 1 and 2, this is accomplished by circulating a drying medium through said passage 8 from one end to the other thereof either in a direction opposite to that in which the material is advanced through said passage or in the same direction. For this purpose, I have provided a suitable blower or fan 25 having its inlet connected by a pipe 26 to the inlet end of the cylinder 3, said pipe being shown as communicating with an opening 21 formed in the head 24. The discharge from the blower is connected by a pipe 28 to an opening 29 in the head l2. With these connections, the blower will cause a circulation of the drying medium through the helical passage in the direction of the arrows c which is countercurrent to the direction in which the material 22 is being advanced through said helical passage. 7

30 indicates a heater in the conduit 28, the purpose of which is to heat the drying medium delivered from the blower so that the drying medium which is admitted to the cylinder 3 through the inlet 29 may have the desired temperature.

During the rotation of the drying cylinder 3, the lower portions 55 of the helical passage 8, that is, the portions of said passage in the lower part of the cylinder, will be more or less filled with the tumbling material 22, and as the drying medium is obliged to pass through such portions of the helical passage in its movement from the inlet opening 29 in the head I2 to the air discharge port 21 inthe head 24, the entire body of the moving current of drying medium will pass repeatedly through the tumbling material in said portions 55 of the helical passage, thus resuiting in ayery efiectlve drying action.

The discharge passage [4 is provided with a revolving gate or valve device 3| which has a= construction similar to the familiar revolving doors that are frequently used at the entrance to buildings. This revolving gate allows the passage therethrough and discharge from the cylinder of the dried material, but does not permit any appreciable amount of drying medium to escape therethrough. I have also herein shown the mouth 32 of the hopper, II as provided with a swinging gate 33, the purpose of which is to prevent the suction at the discharge port 21 from drawing air in through the hopper.

When the drying of a batch of material has been completed and it is desired to clean all the material from the cylinder, such operation can be greatly facilitated by circulating the drying me- 75 dium through the helical passage 8 in the same direction in which the material is moved through said passage, that is, in a direction opposite to that shown by the arrow in Fig. 1.

5 To accomplish this I have shown a by-pass connection 40 connected at one end to the discharge pipe 23, and at the other end to the inlet pipe 23, and a second by-pass pipe ll connected at one end to the inlet pipe 26 between the pipe 40 and the blower, and connected at its other end to the discharge pipe 23 between the by-pass I. and the head l2. 42 indicates a shutofi valve or slide by which the inlet pipe 28 can be closed between the points where the by-pas pipes ll and II are connected thereto and 43 indicates another shutofl valve or slide by which the discharge pipe 28 can be closed between the points where the by-pass pipes 40 and 4| are connected thereto. 44 is a shutoff valve or slide by which the by-pass 40 can be closed, and 43 is a similar shutoff valve or slide by which the by-pass ll can be closed.

When the drying medium is to be circulated in the direction of the arrows c, Fig. 1, then the valves 44 and 45 are closed and the valves 42 and 43 are opened, and with this arrangement, the inlet of the blower 25 is connected through the pipe 26 with the port 21 in the head 24, while the discharge irom the blower is connected by the pipe 28 to the port29, and thus the drying medium will be circulated through the apparatus in the direction indicated by the arrows in Fig. 1.

If it is desired to reverse the direction of movement of the drying medium through the helical passage so as to cause said medium to travel through the passage in the same direction as that in which the material being dried is being advanced, the valves 62 and 63 will be closed, and the valves and 45 will be opened. With this arrangement, the pipe 23 will be connected to the inlet of the blower through the by-pass 4|, and the discharge end of the blower will be connected to the pipe 26 through the by-pass 40, as a result of which the current will be drawn from the cylinder 3 at its right hand end, Fig. l, and delivered to the cylinder at its left hand end and will, therefore, travel through the helical passage 8 in the same direction as that in which the material being dried is moving.

The movement of the gaseous medium through the helical passage in the same direction as that in which the material being dried is moving will assist the advancing movement of said material so that by operating the cylinder for a short time without feeding any fresh material thereto, said cylinder will soon be emptied of all the material therein.

In Fig. 3, I have shown a different embodiment of the invention, wherein the drying of the material as it is being advanced through the helical passage is accomplished by applying heat externally to the cylinder.

In Fig. 3, the cylinder 3 with the core 5 and helical web or vane 6 which forms the helical passage 8 together with the lifting vanes I 5, the feed hopper H and the discharge pipe H are constructed as shown in Figs. 1 and 2.

In the device in Fig. 3, however, there is provided a furnace or heating chamber beneath the cylinder 3 by which heat can be applied to the cylinder externally thereof. This furnace or heater 50 is shown as provided with a burner pipe 5|, through the operation of which the necessary heat is produced.

During the rotation of the cylinder 3. the material is lifted by the lifting vanes l and dropped onto the inclined helicoidal surface It) and thus given an advancing movement as it slides down said surface, and the heat which is applied externally to the cylinder is transmitted to the material through the walls of the cylinder and thus the material is dried.

Where the material being dried is of a powdery nature, the air in the upper part of the cylinder will become dustladen due to th tumbling movement of the powdery material. But since in the construction shown in Fig. 3 there is no circulation of drying medium through the helical passage, the dust suspended in the air-in the cylinder will remain therein instead of being carried out of the cylinder, as would be the case if a current of drying medium were circulated through the passage, as in the construction shown in Fig. 1. The total length of the helical drying passage 8 is many times greater than the total length of the cylinder and, therefore, with this invention it is possible to obtain the advantages of a relatively long drying chamber within the confines of a relatively short fioor space.

Any suitable or usual provision (not shown) may be made for the discharge of moisture-laden air from the cylinder shown in Fig. 3.

I claim: A drier comprising a horizontal cylindrical drying chamber having an axial core extending from one end to the other thereof and also having a helical web encircling the core and extending from the latter to the wall of the cylinder, thereby forming a helical passage extending from one I end to the other of the cylinder, said web having helicoidal faces forming opposed sides of the passage, means to deliver the material to be dried to the passage at one end thereof, said drying chamber having a discharge opening at the other end of the passage, means to rotate the drying cylinder in a direction to cause the material which is given a tumbling motion by said rotation to be advanced gradually through said helical passage by the helicoidal surface of the web, a fan, pipes connecting each end of the cylindrical drying chamber to both the inlet and the discharge outlet of the fan, and valves controlling said pipes whereby the gaseous medium delivered from the fan may be circulated through the helical passage in either direction.

ARTHUR G. GAUTREAU. 

